1. Field of the Invention
The present invention relates to the field of electronic radar, and more particularly to apparatus for reducing the operating requirements on a linearizer by accounting for non-linearities in the transmitted waveform via processing in the radar receiver.
2. Description of the Related Art
A frequency modulated continuous wave (FMCW) radar system often uses linear frequency modulation to provide accurate range information. The resolution of the ranging information is directly dependent on the linearity of the transmit signal. A great deal of prior art exists related to linearizers. For example, applicant owns U.S. Pat. Nos. 5,642,081 and 5,379,001, both directed to closed loop linearizers. The entire contents of U.S. Pat. Nos. 5,642,081 and 5,379,001 are hereby incorporated by reference. Applicant also owns U.S. Pat. Nos. 5,172,123 and 4,692,766, which are directed to linearizers for FMCW radar transmitters, and the entire contents of U.S. Pat. Nos. 5,172,123 and 4,692,766 are hereby incorporated by reference.
Other prior art related to linearizers are found in U.S. Pat. Nos. 4,539,565, 4,593,287 and 4,754,277, all assigned to The Boeing Company. U.S. Pat. No. 5,189,427 assigned to U.S. Philips Corporation also relates to FMCW radar linearizers.
The prior art corrects for non-linearities in the transmitted waveform via further processing in the transmitter, which makes the transmitter circuitry unduly complicated. What is needed is a circuit which can correct for non-linearities in the transmitted waveform without unduly increasing the operating requirements on the transmitter circuitry.